1. Technical Field
The present invention relates to an apparatus and a method for controlling a speed of a motor, and more particularly, to an apparatus and a method for controlling a speed of a motor capable of reducing noise and vibration generated from a motor due to a sudden change in speed, by changing sudden speed variation (indicating a change in speed) as much as a specific ratio for every constant period at the time of controlling a speed of a motor and applying the changed speed variation to the motor step-by-step.
2. Description of the Related Art
Various configurations of a motor control circuit have been known. One of the configurations is the very H-bridge or full bridge configuration. In the H-bridge or full-bridge configuration, four transistors form an H pattern, together with a motor coil connected so as to form an H-shaped bridge. Transistor switches are formed in pair and are controlled. When a first switch pair is conducted, a first voltage signal is applied to the motor coil to generate current flowing in a first direction to the coil and when a second switch pair is conducted, a second voltage signal is applied to the motor coil to generate current flowing in an opposite direction to the coil. A speed of a motor is controlled according to a turn-on/off ratio of the transistor pairs.
FIG. 1 is a diagram schematically illustrating a configuration of an example of an apparatus for controlling a speed of a motor according to the related art.
Referring to FIG. 1, the apparatus for controlling a speed of a motor according to the related art is configured to include: a duty detection unit 110 that detects a duty according to a speed indication (command) having a pulse width modulation (PWM) signal form supplied from the outside; a speed conversion unit 120 that converts the speed indication (command) into an actual speed value (RPM value) based on the duty detected by the duty detection unit 110; a speed detection unit 130 that detects the actual speed of a motor 170; an error calculation unit 140 that calculates a difference (error) between a speed detected by the speed detection unit 130 and a speed converted by the speed conversion unit 120; a speed control unit 150 that outputs a new speed indication value to the motor 170 based on the speed error obtained by the error calculation unit 140; and a PWM generation unit 160 that generates the PWM signal actually applied to the motor 170 based on the speed indication value output from the speed control unit 150.
However, in the apparatus for controlling a speed of a motor according to the related art having the foregoing configuration, when the speed of the motor 170 is suddenly changed, overcurrent flows in a rotator and/or stator winding of the motor 170, such that the motor generates noise and vibration.